1. Field of the Invention
The present invention relates to a unique non-woven fabric and a method for producing the same, particularly, to a non-woven fabric formed of a continuous filament of synthetic fiber, having a structure and an appearance as if staple fibers are mixed therewith and having an excellent softness and pilling resistance suitable for high class clothing, and a method for producing the same.
2. Description of the Prior Arts
In the past, a typical non-woven fabric was a felt utilizing a milling property of wool. Since then, many non-woven fabrics formed of a web of synthetic staple fibers or a layered sheet of synthetic filament fibers having a non-milling property have been proposed, which web or sheet is punched by needles or water jets to cause the composing fibers to become entangled.
Some of these non-woven fabrics are used as a final product without further treatment, and the others are post-treated to strengthen the mutual entanglement or bonding between fibers by resin impregnation or by press-heating.
The production system using the staple fiber web as a starting material has an advantage in that fibers are easily entangled by needle-punching or the like. This system, however, has a drawback in that a web having a uniform thickness is not easily produced from a lump of staple fibers through a carding engine, especially when the fibers are long staple fibers of ultra-fine denier suitable for clothing manufacture. In this case, the resultant web has an uneven quality and many cloudy portions where the fibers are not fully separated from each other. Thus, this problem constitutes a bar to the production of a non-woven fabric having light weight, excellent softness and uniform thickness. Especially, when the fiber web is resin-coated, a resin membrance is unevenly formed on the web surface, and thus the reinforcement effect of the resin-coating can not be attained.
To improve the softness of the non-woven fabric for the manufacture of clothing, various methods have been proposed. For example, a fiber web is prepared by a composite fiber having an island-in-sea type structure and, thereafter, the sea component of the fiber is removed so that the island component remains as an ultra-fine fiber, or alternatively, a web is prepared by a splittable conjugated fiber composed of different kinds of polymers and is post-treated to divide the conjugated fiber into the individual components. These techniques, however, require a sophisticated spinneret structure for extruding such a composite fiber, which tends to make production management difficult. Moreover, an additional process is required for obtaining the component fiber from the original fiber. Thus, the process becomes complicated and the production cost very expensive.
According to a system for the production of a layered web sheet from a continuous filament fiber spun directly from a spinneret, usually referred to as "a spun bond system", an ultra-fine fiber such as that one having a 0.5 denier is usable because the fiber thickness has little influence on the evenness of the resultant fiber web relative to the former system using a staple fiber web prepared from a carding engine. Even in this system, however, the resultant non-woven fabric has a drawback in that the fibers in the fabric are liable to be displaced in the web when an external force is applied, since the migration and the mutual entanglement of the fibers are not enough even after they are subjected to powerful water-jet punching during the web forming process. This relatively loose structure of the fabric results in a tendency toward pilling or napping on the fabric surface and is one reason why the non-woven fabric obtained by the latter system is not utilized in the manufacture of clothing.
In general, to avoid the abovesaid pilling or the like, the fiber web forming the non-woven fabric is impregnated with a resin or is subjected to a heat-adhesion treatment to reinforce the bonding between the fibers composing the web. The fabric thus obtained, however, tends to lack the desired soft touch and to lose air-permeability, and in addition, a paper-like, annoying sound is generated when touched. These are fatal drawbacks for clothing manufacture, even though usable for industrial purposes.